1. Field of the Invention
The present invention relates to a portable telephone and, more particularly, to a portable telephone capable of selectively effecting analog or digital communication on receiving an analog or digital signal.
2. Description of the Related Art
A portable telephone having the above-mentioned capability is extensively used today and generally made up of an antenna, a handset, a radio section, an analog signal processing section and a digital signal processing section for processing signals particular to analog communication and digital communication respectively, a first common signal processing section connected to the radio section for selectively modulating or demodulating an analog or a digital signal, a second common signal processing section connected between the two signal processing sections and the handset for executing filtering, analog-to-digital (AD) conversion and other preprocessing, and a control section for selectively applying power to either of the two signal processing sections. In the event of analog communication, for example, the control section prevents power from being applied to the digital signal processing section which does not join in the communication thereby saving power.
However, the conventional portable telephone has a problem that both of the first and second common signal processing sections have to operate with no regard to the type of communication i.e., analog or digital. Hence, the power to be consumed by these signal processing sections is required.